that is in obama ads and in his own statements. listen. >> president obama knows that women being paid 77 cents on the dollar for doing the same work as men isn't just unfair, it hurts families. >> if you do the same work as a man, you ought to be paid the same wage as a man. [applause] >> reporter: now, of course, the problem is that's not true. the assertion that it's equal work for equal pay -- equal pay for equal work. the census data don't say women make 77 cents on the dollar for the same work. a census official briefing reporters was recently asked if it measures equal pay. here's what he said. >> so i don't want -- i guess we don't have a way of measuring equal pay for equal work. we try to compare the earnings of full-time year-round work between men and women. >> reporter: so, arthel, if the 77 cents isn't a measure of equal pay for equal work, what is it? a rough measurement of all women's wages versus all men's wages, definitely not a measure of equal pay for equal work. arthel? arthel: by the way, i said what's the big